@InfraBlue,
I made an assumption that it is kind of hard to have a temple with priests when people are traveling around and hunting from meal to meal. They sort of live where they set up camp. In larger groups tasks (like shamanism) can be assigned to individuals along with other vocations related to skills.
This doesn't mean that rituals can't be performed by wandering hunter gatherers but rituals often require a community. For instance, ritualized dance is not very much fun when it is only between 8 or so people and who would play the drums and who would watch out for wild animals approaching the campsite? And oh boy, you get to dance with your sister... mating rituals are less fun with family members
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It just seems logical that a community does rituals better and this also facilitates trade and possibly even agriculture because they can settle down to one geographic area and build more permanent structures than lean tos and seasonal caves that are sometime prone to flooding whenever it rains.
Hunter gatherers did have rituals but not as sophisticated as when they began to develop communities with trade and had more people to assign duties to.
It is a logical assumption that communities do ritual better than an handful of solitary travelers. Even cave dwellers may have had a function in a larger community. Some travelers may have been hostile to other travelers and it was likely a to each their own affair.
Even animals when in larger communities are more likely to exhibit ritualized behavior.
I am sure that many hunter gatherers respectfully buried their dead but there was no whole town to mourn and throw a wake.
Communities are the very definition of being "civilized".
Just like when the western US was settled, many people left in a wagon and found a piece of land and squatted way out in the middle of nowhere.